Impact of Reservoir Fluctuations on Cracking and Erosion: Physical Modeling and Numerical Investigation

Climate projections indicate that increasing precipitation variability and extreme storm events will intensify reservoir-level fluctuations, escalating the risk of overtopping and seepage in earthen embankments. These processes accelerate surface cracking, internal erosion, and slope instability, particularly in levees constructed with plastic or fine-grained soils. This study investigates the influence of soil composition on crack development and levee response under controlled flooding scenarios, with a focus on representative soils from the Missouri River Basin. Two small-scale physical levee models were constructed using alluvial and mixed (alluvial-loess) soils and subjected to simulated flooding events that mimic both prolonged inundation and flash flood conditions. High-resolution imagery of the downstream slope was collected over time and analyzed using a custom Python-based image processing workflow. The method combined HSV-based soil masking, contrast enhancement, adaptive thresholding, and edge detection to quantify crack coverage throughout the experiments. Results showed that the alluvial soil model exhibited earlier and more extensive cracking, reaching up to 49% surface coverage, while the mixed soil model displayed a delayed and more moderate response. Additionally, numerical modeling was conducted to incorporate reservoir-level fluctuations and support experimental findings.